回调函数问题 [英] Callback functions problem
问题描述
Hello ther
我在某地读过回调函数应该是全局的还是静态的
成员函数。
1：我可以使用静态成员函数，但我怎么能访问成员
类不是静态的。
2：我可以使用全局函数但想要访问类的成员。
让我知道可能的解决方案。
问候，
Ajay Sonawane
< aj *********** @ gmail.com>在消息中写道
news：11 ********************** @ o13g2000cwo.googlegr oups.com ...Hello ther
我在某地读过回调函数应该是全局的还是静态的
成员函数。
1：我可以使用静态成员函数但是如何访问成员呢
非静态的类。
2：我可以使用全局功能，但想要访问班级成员。
让我知道可能的解决方案。
问候， Ajay Sonawane
我使用过的大多数回调函数都提供了一个void *指针，通常是一个名为userData或类似的
，这就是你可以像你一样使用
。我所做的就是编写一个全局回调函数，并输入
void * thethis想要接收回调的对象的指针。
然后，在回调中，我只是将void *指针转换为指向我的
类的指针，然后使用它调用该对象上的成员函数来执行回调的实际工作。
-Howard
您可以尝试使用友元功能。这将为您提供全局功能
，也可以访问会员数据。
< aj *********** @ gmail .COM>在消息中写道
news：11 ********************** @ o13g2000cwo.googlegr oups.com ...Hello ther
我在某地读过回调函数应该是全局的还是静态的
成员函数。
1：我可以使用静态成员函数但是如何访问成员呢
非静态的类。
2：我可以使用全局功能，但想要访问班级成员。
让我知道可能的解决方案。
问候， Ajay Sonawane
" kloodge" < mg@aol.com>在消息中写道
新闻：mJ ***************** @ tornado.texas.rr.com ...
请不要顶尖。 [重新安排]
< aj *********** @ gmail.com>在消息中写道
新闻：11 ********************** @ o13g2000cwo.googlegr oups.com ...你好，我在某地读过回调函数应该是全局的还是静态的
成员函数。
1：我可以使用静态成员函数但是我怎样才能访问类的成员
不是静止的。
2：我可以使用全局功能，但想要访问班级成员。
让我知道可能的解决方案。
问候，
Ajay Sonawane
您可以尝试使用友元功能。这将为您提供一个全局功能
，也可以访问会员数据。
虽然友情功能允许您访问对象的私人或
受保护的成员，在这种情况下它没有帮助，因为静态成员或
全局函数没有该类的实例来操作。
的问题是关于访问非静态成员，这意味着他需要一个
类的实例来操作。友谊只会影响能见度。
-Howard
Hello ther
I read somewhere that callback function should be global or static
member function.
1: I could use static member functions but how could I access members
of class which ar not static.
2: I could use global function but want to access members of class.
Let me know the possible solutions.
Regards,
Ajay Sonawane
<aj***********@gmail.com> wrote in message
news:11**********************@o13g2000cwo.googlegr oups.com...Hello ther
I read somewhere that callback function should be global or static
member function.
1: I could use static member functions but how could I access members
of class which ar not static.
2: I could use global function but want to access members of class.
Let me know the possible solutions.
Regards,
Ajay Sonawane
Most callback functions that I''ve worked with provide a void* pointer, often
called userData or something similar, which is there for you to use as you
see fit. What I do is write a global callback function, and put in that
void* the "this" pointer of the object which wants to receive the callbacks.
Then, in the callback, I simply cast the void* pointer to a pointer to my
class, and use it to call a member function on that object to do the actual
work of the callback.
-Howard
You may try using a friend function. This would give you a global function
that can also access member data.
<aj***********@gmail.com> wrote in message
news:11**********************@o13g2000cwo.googlegr oups.com...Hello ther
I read somewhere that callback function should be global or static
member function.
1: I could use static member functions but how could I access members
of class which ar not static.
2: I could use global function but want to access members of class.
Let me know the possible solutions.
Regards,
Ajay Sonawane
"kloodge" <mg@aol.com> wrote in message
news:mJ*****************@tornado.texas.rr.com...
Please don''t top-post. [Re-arranged]
<aj***********@gmail.com> wrote in message
news:11**********************@o13g2000cwo.googlegr oups.com...Hello ther
I read somewhere that callback function should be global or static
member function.
1: I could use static member functions but how could I access members
of class which ar not static.
2: I could use global function but want to access members of class.
Let me know the possible solutions.
Regards,
Ajay Sonawane
You may try using a friend function. This would give you a global function
that can also access member data.
While a friend function will allow you access to an object''s private or
protected members, it does not help in this case, because a static member or
global function does not have an instance of that class to operate on. The
question was about accessing non-static members, which means he needs an
instance of the class to operate on. Friendship only affects visibility.
-Howard
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